Earth's Magnetic Field Probably Won't Flip after All, New Study Claims

North hasn't always been north—in fact, the North and South poles have essentially flipped positions many times in Earth's history, usually every 200,000 or 300,000 years or so. By that schedule, we're theoretically overdue for the next magnetic realignment.

A magnetic field reversal is not the sort of thing we necessarily want to live through firsthand—it would temporarily weaken the shield protecting us from some of the most harmful side effects of the sun—but the phenomenon remains a mystery because it's never happened with scientists around to watch.

Scientists are developing odds for such an event and have some good news: according to a new paper published in the journal Proceedings of the National Academy of Sciences, what's happening now doesn't match what happened during previous incidents. They suspect that the magnetic field will calm down again without further eventfulness.

The prospect of a magnetic field flip has made it into the imaginations of apocalypse theorists as well as geoscientists. "This is certainly a 'hot' topic in this moment, to which no definite answer has been reached yet," Carlo Laj, a geoscientist at the Ecole Nationale Superieure in France, wrote in an email to Newsweek.

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Although you probably don't spend much time worrying about which way is north, it's a good thing that scientists do. For more than a century, Earth's magnetic field has been weakening, and scientists don't really understand why.

That's already letting in more harmful radiation, which has damaged satellites orbiting Earth. If it continues, it could cause holes in the ozone layer, similar to the human-induced one over Antarctica that is gradually healing. (But even in the case of a complete flip, Earth would never be left completely unprotected.)

"The field doesn't have to go to a reversal for this modulation to be important for societal reasons," John Tarduno, a geophysicist at the University of Rochester in New York, told Newsweek. "It's important now."

The scientists behind the new paper compared what's happening now to what happened during two previous episodes—about 41,000 years ago and about 34,000 years ago—calledexcursions. That's what scientists call it when the field appears to have flipped in parts of the world, but then return to its previous state without ever reversing globally. It might not be obvious enough to affect your daily life, butit would definitely be a big deal for geoscientists.

Given the current weakening, an excursion is one of three possible scenarios for what could soon happen. The field could also fully reverse, or it could go back to normal.

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The aurora are caused by charged particles from the sun slipping through Earth's protective magnetic field. Stringer/Reuters

Comparing present data with previous excursions, the scientists foundthe two scenarios don't seem to match up very well, which they think means the magnetic field will settle down.

Laj isn't convinced the new paper clarifies the situation and argued that in its desperation for more data, it might be diluting what that data can actually tell us. The authors are trying to piece together a global history of thousands of years of magnetic activity, but the data they can use to do so is neither global nor constant. It's also difficult to interpret clearly, Tarduno said, since the magnetic alignments it records can change over time.

Whatever happens to the magnetic field, scientists should have plenty of time to understand what comes next. While it has been longer than they would expect since the last reversal, there's no sign anything is changing fast.

"Even at the most outrageous scenarios, this is not going to happen until more than a thousand years into the future," Tarduno said.

Earth's Magnetic Field Probably Won't Flip after All, New Study Claims | Tech & Science